Perhalocyclohexanes



Patented Aug. 23, 1949 PERHALQCYCLOHEXANES Vincent V. Lindgrem, West Lafayette, and Earl T. McBce, La Fayette, Ind., assignors. to Purdue Research Foundation, West, Lafayette, Ind., a corporation of Indiana No Drawing. Application. June 75.1946, Serial, No. 675,29I

4, Claims. 1

This. invention relates to organic compounds designated as the perhalocyclohexanes and more specifically to. the fluorine contain ng perhalocyclohexanes having from one to five halogen atoms other than fluorine in the molecule.

The compounds in general are verystable, heatresistant organic compositions, the lowest member of the series, 1. e., the. compound containing one chlorine atom, boiling at about '17. degrees Centigrade, and other members boilin at. higher temperatures depending upon, the number of halogen atoms other than, fluorine therein. Thepresence of only carbon and halogen atoms in the molecule greatly enhances the stability of these compounds, and due to their stability and, their heat-resistant qualities, the compoundsare useful as dielectrics, heat-transfer media, insulating liquids, transformer fluids and. so. forth. Some of these compounds also exhibit lubricating properties.

The compounds may be prepared, for example, by reacting an appropriate bromoor chlorosubstituted benzene with manganese trifluoride or other suitable halogenating agent maintained in a finely granulated form at high temperatures;

The bromoor chloro-substituted benzene may he vaporized into a series of manganese trifluoride reactors, maintained at, a suitable temperature,

g. to 450 degrees. Centigrade. The manganese irifluoride reactors may be constructed of a low-carbon sheet steel and may be five feet long. six inches wide and one inch deep. Each reactor may be equipped with its own individual heating unit, to allow the maintenance of temperature at any desired level. The unit may be equipped with suitable inlets, outlets, and thermometer wells, and may be insulated with mag-- nesia covering. Each unit may contain approximately moles of manganese trifluoride. It may be found advantageous, if a series of such units is used, to maintain the reactors at successively higher temperatures, i. e., to maintain the first reactor slightly above the boilingpoint of the starting material, the remaining reactors in the series being maintained at a temperature slightly above that of the preceding unit in the series. In this manner the bromoor chlorobenzene is subjected to the reaction with manganese trifiuoride first at the low temperature, and the partially fiuorinated product from the reaction at this low temperature is then reacted with additional manganese trifluoride at successively higher temperatures. This is ad vantageous in view of the fact that, the additional fluorine in the cyclic nucleus makes the compound more heat-resistant and less decomposition occurs, resulting in higher yields of fluorinated product. It may also be found advantageous to untain the reactors during the first contact with the, br0moor chlorobenzene at a relatively low temperature, and then to recycle the artially fluorinated' product from the first reaction at an increased temperature, increasing the amount of fluorine in the molecule with each passage of the organic material through the reactor. The organic product may then be condensed in iced receivers, washed with dilute alkali or water and rectified.

The following examples indicate methods by which members of the new group of compounds maybe prepared, but are in no way to be con strued as limiting the invention thereto-z Example 1 C ne hundred and forty-seven grams of ortho-. dichlorobenzene was placed in a nicke1 vaporizer, heated to its vaporizing temperature, and nitrogen vapors passed therethrough. The orthodiehlorobenzene was carried by the nitrogen into a series: of reaction units containing approximately 50 gram moles of silver difluoride. Six reaction units were utilized in the operation, the temperature of each reactor being slightly higher than that of the preceding unit. The units were thus maintained at 118, 123 150, 165, 190 and 200 degrees centigrade, while orthodichlorobenzene introduced. After all of the organic material had been intr-oduced into the reactor, the passage of nitrogen through the apparatus was continned for several hours in order to expel all of the product from the reactor. A recovery of 194 grams of liquid was made from the first run.

The temperature of the reactor was then raised,

and the product from the preceding run was recycled, the individual units in the reactor being maintained at 142, 166, 226, 250, 285, and 323 degrees centigrade. Nitrogen was used to purge the reactor as in the previous run, and a batch of colorless organic liquid weighing 149 grams was recovered.

3 An additional 147 grams of orthodichlorobenzene was treated with silver difluoride in the reactor. The units of the reactor in this case were maintained at 123, 135, 159, 178, 195 and 227 defluorocyclohexane, (2) 114.8 grams of dichlorodecafluorocyclohexane. The analyses and physical properties of these two compounds are listed in the table below.

Per Cent F Per Cent 01 M. W. Compound B.P.,C. 1' 'O '5 Found Found isla- Fmmd as grees centigrade. The purpose of this reaction was to obtain more starting material for a final 5 Example 3 recycle. The organic product weighed 244 grams. A single unit iron reactor containin moles The product from the previous reaction was of lead tetrafluoride was assembled as usual and recycled with the various units maintained at equipped with an iron vaporizing chamber. 196, 230, 275, 295, 315 and 325 degrees centigrade. n -h f m le of h xachl ro n ne. 14 m Approximately 200 grams of a colorless organic 20 was placed in the vaporizer and the vaporizer and liquid was bt i d from t l reactor heated to about 300 degrees centigrade. The products from the two recycling opera- By passing nitrogen through the vaporizer, the tions were combined and once more recycled in e ac o n e as por ed nto the rethe reactor the units being maintained at 288 actor where fluorination occurred. After six 296, 297, 323 and 335 degrees Centigrade during h r f i p r 85 grams f rin ed the run in order to ensure satisfactory fluorinaproduct was obtained. From the mixture was tion. Nitrogen was again used to purge the re- Separated 15 g a f trichlomnonafluorocycloactor after all of the organic material had been h x n on i n p n r ne nd introduced. When the product from this run p r n r n The po nd b ils at about was poured over ice, the organic layer which sep- 8 d s Centigrade e heoretical arated weighed 246 grams. The organic product h lo n on en f the p d is p n was distilled to remove the greater portion of lowfluorine and per Cent r eboiling material. Rectification of the residue Other members of this group of C DOundS yielded 50 grams, boiling from 75 to 80 degrees Which may be prepared as previously described centigrade and 15 grams boiling at 110 degrees 35 include bromounclecafiuorocyclohexane, dibromocentigrade. The remainder of the product sepdecafiuorocyclohexane, tribromononafluorocycloarated from the rectification consisted of lower, hexane, tetrachlorooctafluorocyclohexane, tetraintermediate, and higher fractions. The lower bromooctafiuorocyclohexane and pentachlorocut consisted. of chloroundecafiuorocyclohexane heptafluorocyclohexane. These compounds may and the second cut consisted of dichlorodecafiube obtained by using as starting material a orocyclohexane. bromoor chlorosubstituted benzene which contains at least the same number of bromine or Eimmple 2 chlorine atoms as the desired bromoor chloro- A reactor comprising two iron units, each confluorocyctohexanfi taining approximately 20 moles of manganese We (31mm: trifluoride was set up with suitable heating units. A pemalocyclohexane contammg Two hundred and ninety-two grams of orthodiand fiuorme as e only halogens, where1n chlorobenzene was introduced into this reactor groups are present m the and from a dropping funnel during ninety minuteswherem the number of chlorine atoms is from one The reactor was maintained at about 230 degrees to three mcluslve- Centigrade. The reactor was purged with nitrocmoroundecafiuorocyclohexanegen for two hours and 345 grams of partially DnPhlorodecafiuorocyclohexanefiuorinated material isolated. The reactor was Tncmorononafluomcyclohexaneregenerated with fluorine and the temperature VINCENT LINDGREN- then raised to about 400 degrees centigrade. EARL MCBEE- The reactor was purged with nitrogen for two hours and 345 grams of partially fluorinated ma- REFERENCES CITED terial isolated. The reactor was regenerated The following references are of record in the with fluorine and the temperature then raised to file of this patent: about 400 degrees centigrade. The material from the first pass was recycled through the re- UNITED STATES PATENTS actor at this temperature during two hours. Number Name Date After purging with nitrogen, 410 grams of prod- 2,404,374 Harmon July 23, 1946 uct was obtained. This fiuorinated .product was recycled again at a temperature of about 450 de- OTHER REFERENCES grees centigrade in order to ensure the desired Bigelow et al. J. A. C. S., 56, 2773-4 (1934),. degree of fluorination. The product weighed 408 Simons et al. J. A. C. S., 61, 2962-66 (1939). grams. From this mixture of halogenated com- Fukuhara et al. J. A. C. 8., 63, 2792-5 (1941). pounds was separated by rectification two frac- Henne et al. J. A. C. 8., 67, 1235-7 (1945). tions as follows: (1) 96.2 grams of chloroundeoa- 70 

